Why does Boarderlands 2 have sexual themes and what is the sexual themes

Honestly tell you, I'm not sure as to where it is in the game. It is probably something hidden or a point in game that you haven't reached yet. As for a definition, sexual themes is a very broad topic. This can range anywhere from saying sexually languages words in game, to any type of audio, video that is sex related, or any references to anything sexual. Again, it is a very broad topic so that makes it a little difficult to pinpoint an exact definition. Hope this helps!